1. Field of the Invention
The present invention relates to an automatic transmission of a vehicle. More particularly, the present invention relates to a 2-3 up-shifting shift control device of an automatic transmission of a vehicle, and a method thereof.
2. Description of the Related Art
Generally, in an automatic transmission used for a vehicle, a shift control system performs control to realize automatic shifting into different speeds and shift ranges according to various factors including throttle valve opening, vehicle speed and load, and several other engine and driving conditions sensed through a plurality of sensors. That is, based on such factors, the shift control device controls a plurality of solenoid valves of a hydraulic control device such that hydraulic flow in the hydraulic control device is controlled, resulting in shifting of the transmission into the various speeds and shift ranges.
In more detail, when the driver manipulates a shift lever to a particular shift range, a manual valve of the hydraulic control device undergoes port conversion as a result of the manual valve being indexed with the shift lever. By this operation, hydraulic pressure supplied from a hydraulic pump selectively engages a plurality of friction elements of a gearshift mechanism according to the duty control of the solenoid valves, thereby realizing shifting into the desired shift range.
In such an automatic transmission, shift quality is determined by how smoothly the friction elements are engaged and disengaged. Namely, when changing shift ranges, the timing between the engagement of a specific set of friction elements and the disengagement of another specific set of friction elements determines the shift quality of the automatic transmission. Accordingly, there have been ongoing efforts to develop improved shift control methods that enhance shift quality by better controlling the timing of friction elements to engaged and disengaged states.
In the automatic transmission described above, shift control is performed for up-shifting from the first forward speed to the fourth forward speed in turn, down-shifting from the fourth forward speed to the first forward speed in turn and down-skip shifting 4-2 or 3-1, according to the driving condition of a vehicle.
The 2-3 up-shifting shift control of the prior art performs shifting from the 2 driving range into the 3 driving range according to driving speed (output shaft rpm). In such a 2-3up-shifting shift of the prior art, a combination of only two intermediate solenoid valves is applied during the entire shift in order to ensure hydraulic control and shift quality maintenance during the shifting.
Accordingly, the degrees of freedom of hydraulic control are minimal when applying the combination of just two intermediate solenoid valves in 2-3 up-shifting, and the hydraulic control and shift quality maintenance is difficult to ensure without taking into account throttle valve opening. In addition, shift shock from interlocking frequently occurs.
It is an object of the present invention to provide a 2-3 up-shifting shift control device of an automatic transmission of a vehicle and a method thereof to reduce shift shock in shifting from a 2 driving range to a 3 driving range, and to improve the endurance of an automatic transmission.
To achieve the above object, the present invention provides a 2-3 up-shifting shift control device of an automatic transmission, comprising a vehicle speed sensor sensing a vehicle speed, a shift lever position sensor sensing a shift lever position of the vehicle, a throttle position sensor sensing a throttle valve opening of the vehicle, a shift control unit outputting a 2-3 up-shifting drive control signal corresponding to the sensed throttle valve opening when the shift lever position is changed from a 2 driving range to a 3 driving range and the vehicle is driving, and a shift drive unit performing a predetermined 2-3 up-shifting drive control operation by controlling hydraulic pressures in response to the control signal received from the shift control unit.
To achieve the above objective, the present invention provides a shift control method of an automatic transmission comprising the steps of sensing the vehicle speed, sensing the shift lever position of the vehicle, sensing the throttle valve opening of the vehicle, determining a shift control condition corresponding to the sensed throttle valve opening when the shift lever position is changed from the 2 driving range to the 3 driving range and the vehicle is driving, and performing the 2-3 up-shifting control operation according to the determined shift control conditions.
Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.